Abstract:Qn2 of Daqingzijing oil field sees a great potential in oil and gas resources. In this paper, with Daqingzijing oil field as the study area, the formation mechanism of hydrocarbon reservoir is comprehensively analyzed, including studies of core, geology log, seismic and well log. With the "facies-potential-transport ternary reservoir controlling" theory, sedimentary facies, sedimentary evolution, storing characteristics, pressure potential, fluid potential, carrier system, and the correlation of these factors and hydrocarbon are discussed. A pool-forming pattern of hydrocarbon-rich depressions is proposed, with the reservoir rock of the depression as the delta front sandstone. It is suggested that the underwater distributary channel and the mouth bar sand of a large scale, with good reservoir properties, are favorable sedimentary facies. Slopes of depression belong the low-potential zone. Fault and bedded sandstone are combined, to form a T-passage system. Fluid potential drives hydrocarbons to flow through the T-passage system, to be accumulated in the high-quality facies. Reservoir formation is controlled by facies and potential and carrier system. Reservoir types in research area see a distribution of a zoning feature. The west slope of synclines sees more growth of fault-lithological and fault block oil pools. The east slope of synclines sees more growth of up-dip pinchout of sandstone-reservoir.